Investigators have found that the pilot of the plane that crashed and killed Emiliano Sala was not licensed to fly the aircraft.
Emiliano Sala, 28, and pilot Dave Ibbotson died in the crash as they were travelling from Nantes to Cardiff on January 21, 2019.
The Argentinian striker had recently signed for Cardiff City, who were in the Premier League at the time.
The Air Accidents Investigation Branch published its findings on Friday.
The report found that Mr Ibbotson lost control of the plane during a manually-flown turn, which was more likely to have happened because the flight was “not conducted in accordance with safety standards applicable to commercial operation”.
It said Sala would have been “deeply unconscious” from carbon monoxide poisoning at the time.
Mr Ibbotson, who was colour blind, had no previous training to fly at night and his SEP rating, which allowed him to fly a single-engine piston aeroplane, had expired three months prior to the accident.
Regarding the nature of the accident, principal inspector Brian McDermid said: “The aircraft was extensively damaged and the wreckage was in three parts, held together by electrical and flying control cables.
“The engine had disconnected from the cockpit area, and the rear section of the fuselage had broken away from the forward section…
“The cockpit area and instrument panel were badly disrupted, such that it would not have been possible with any confidence to determine the position of controls and switches before the crash.”
Pilot, Dave Ibbotson, was never found and presumed dead.